Recorder



April 1942- v R. a. AREY 2,280,613

' RECORDER Original Filed April 7', 1938 Inventor: Ralph G. Arey by 7V6!. J

is Atterney Patented Apr. 21, 1942 UNITED STATES PATENT OFFICE Tz.zso.s1a

RECORDER Ralph G. Arey, Swampscott, Mass aasignor to General ElectricCompany, a corporation of New York Original application April 7. 1938,Serial No.

1939, Serial No. 273,085

3 Claims.

This application is a division of my copending application, Serial No.200,707, flied April 7, 1938. My inventionrelates to recorders and curvedrawing instruments and concerns particularly so-called inklessrecorders or recorders of the type in which the need for a movable penand ink is eliminated. a

It is an object of my invention to provide a recorder with a simpleconstruction and method of operation having the operating and indicatingelements mounted as a single unit behind a chart on a single one pieceframe.

Divided and this application May 11,

with great rapidity and reproducing with high fidelity even sharpfluctuations in the magnitude of the recorded quantity.

It is also an object of my invention to provide a recorder in which thesupply roll is clearly visible so that it may readily be ascertainedwhen the chart needs to be replaced and in which both the re-roll andthe supply roll are accessible to permit convenient adjustment orrenewal of the record chart.

It is another object of my invention to provide a recorder constructionin which a large amount of the chart is visible so that a record curvefor a considerable period of time may be observed 7 without pulling outthe re-roll.

Still another object of my invention is to produce a recorder in whichthe recording operations consume a very small amount of energy and inwhich a single low-power motor may be utilized to drive all elements ofthe apparatus although considerable force is produced for making theimpressions on the record chart.

Still another object is to provide an intermittent marking recorderavoiding stickiness in the deflection o! the movable element of theinstrument and avoiding sticking of the instrument pointer to themarking material or to the pointer striker bar.

Still another object is to provide a recorder I vide a recorder of thetype having a movable marking ribbon in which there is a proper andconstant relationship between the speeds of the chart and the markingribbon, and the chart rec- 0rd will be completed before the ribbon runsout.

Still another object of my invention is to provide a curve-drawinginstrument for measuring a variable quantity which not only records themeasured values of the quantity but also records 10 the time of durationof surges in the case of variations taking place with great rapidity incomparison with the speed of travel of the record chart. I Likewise itis an object of my invention to provide a recording instrument combiningthe advantage of a continuous line recorder for normal conditions and ofa dotted line recorder for surges.

Other and further objects and advantages will become apparent as thedescription proceeds.

My invention may be understood more readily from the following detaileddescription when considered in connection with the accompanying drawingand those features of the invention which are believed to be novel andpatentable will be pointed out in the claims appended here- In carryingout my invention in its preferred form I provide a movable strip chart,a platen behind which the chart is moved and a measuring instrument witha pointer movable behind the chart. There is a ribbon impregnated withmarking material stretched across the chart between it and the platenand a vibrating striker is mounted behind the pointer so as to drive thepointer intermittently against the chart and in this way press theportion 0! the chart in front of the pointer against the marking ribbon,thus producing suitable markings to form a record curve on the chart. Asingle motor is utilized for reciprocating the striker and for advancingboth the chart and the marking ribbon. A pawl and ratchet mechanism isprovided for advancing the strip chart and the speed of the chart ismade adjustable by providing an arrangement for adjusting the throw ofthe chart advancing pawl.

In the drawing Fig. 1 is a perspective view of the mechanism employed inone embodiment of my invention with the depth greatly exaggerated forthe sake of separating the parts and showing them with greater clarity.Fig. 2 is a perspective diagram of the apparatus a: Fig. 1 mounted inits casing and shown in natural proportions. Fig. 3 is a perspectivefragmentary view of a portion of the apparatus of Fig. 1 showing more indetail the relationship between the instrument pointer in the chart andthe arrangement for producing markings on the chart. Like referencecharacters are utilized throughout the drawing to designated like parts.

In the arrangement illustrated in Figs. 1 and 2 there is a chartcarriage secured in a casing i I, which may be either a portable casingor one designed for mounting on a switchboard. It will be understoodthat the casing i i may be provided with a cover i2 which may be openedfor any necessary adjustments of-the mechanism or replacement of thechart and marking material, but the construction is such that the chartcarriage need not be moved for this purpose. The chart carriagecomprises a sheet of metal bent to form a front plate i3 and side platesM, the greater part of the side plates being broken away for the sake ofclarity in the drawing. The side plates provide support for themechanism of the apparatus including the various bearings which are notshown.

A movable strip chart i5 is provided which is designed to pass downwardin front of the front plate iii from a supply roll iii to a re-roll ill.The front surface of the plate i3 defines a plane in which the charttravels. Secured to the side plates M and extending across the upperfront plate It in front of the strip chart i5 is mounted a platen 93. Asuitable indicator or measuring instrument such as a current responsivemeasuring instrument I9 is provided having a movable arm or pointer 20designed to deflect in aplane behind the strip chart iii and parallel tothe front plate 93. A sheet or a strip 2! impreg nated or coated with asuitable marking material such as a strip of carbon paper or atypewriter ribbon, for example, is mounted between the strip chart i5and the platen i8, and a striker 22 consisting of a pivotally mountedbar parallel to the surface of the front plate i3 and extending alongthe marking strip 2| is mounted behind the instrument pointer 20.Suitable means are provided for vibrating or reciprocating the strikerbar 22 toward and away from the front plate i3 so as to drive theinstrument pointer 20 intermittently against the strip chart i5 and inthis manner cause the portion of the strip chart in front of theinstrument pointer 20 to press against the marking strip 2! and producemarkings on the front of the strip chart.

The platen i8 may be formed with a straight edge 23 on its back surfaceand the end 24 of the instrument pointer 20 may be substantiallystraight and parallel to the plane of the strip chart so that, when theinstrument pointer 20 Y is struck by the striker bar 22, there will be apressure point at the intersection of the instrument pointer 24 and thestraight edge 23 at which the marking ribbon 2| and the strip chart I 5will be pressed together. This action produces a mark on the stripchart. In the arrangement shown the straight edge 23 forms the apex of aridge of triangular cross-section and the pointer end 24 is of circularcross section, but it will be understood that both might be of circularor triangular cross-section or any other suitable shape for the purposeof producing on the strip chart IS a well-defined point of the curve 25on the strip chart l5 whenever the bar 22 strikes the instrument pointer24. Preferably, the bar 22 is substantially behind the straight edge 23.It will be apparent that with the arrangement shown, any mark producedon the strip chart l5 for a given position thereof, regardless of the meals angular position of the instrument pointer 20, will be on a straightline across the strip chart it instead of on an are as will be the caseif a flat platen were employed and the end of the instrument pointer 28were bent to form a stylus striking the back surface of the strip chartl5. However, my invention, in general, is not limited to the precisearrangement shown.

I consider it important to mount the marking strip H in front of thestrip chart and the movable pointer 20 in back of the strip chart inorder that the record will be produced on the front of the strip chart,making it unnecessary to employ a transparent strip to have the recordvisible from the front of the instrument while the record is beingproduced, and also preventing the movable pointer from coming in directcontact with the marking material thus avoiding the possibility of thepointer sticking to the marking strip or to the striker bar 22. In thisway what is known as stickiness or sluggishness of the action of theinstrument is is overcome and the angular deflection of its pointer 20responds promptly and continuously to variations in the magnitude of thequantity measured by the instrument Hi. There is no mechanism whichdefiects in front of the chart plane or outside of the casing volumedefined by the chart plane. The instrument striker bar and operatingmechanism as well as the deflecting pointer 20 are mounted inside theplates i3 and I4 and behind the chart 'i 5, for the sake of compactness,for the sake of completely hiding and protecting the instrument andoperating mechanism, in order to avoid covering the chart or preventingit from.

being observed throughout the length of the front plate [3, and in orderto permit conveniently and safely pulling chart off the re-roll I! whenit is desired to examine a greater length of back record.

Preferably, to avoid wearing out the marking strip 2|, it is made in theform of a long movable strip wound upon spools 28 and 21 in a mannersomewhat similar to the mounting of typewriter ribbon on typewriters,and a suitable arrangement is provided for unwinding the ribbon from onespool and rewinding it on the other. In the illustration shown, a spool26 serves as a re-roll and is driven at a speed proportional to thespeed of the strip chart l5 in a manner which will be explainedhereinafter.

I consider it important to provide the striker bar 22 with an actuatingmechanism whereby the bar 22 will strike the pointer end 24 withconsiderable force so as to produce clear records but without theconsumption of more than a very small amount of power in order that thesame motor may be used for actuating the striker bar 22 and advancingthe strip chart and the marking ribbon 2|.

The striker bar 22 forms one side of 9. rectangular striker frame 28which has a central rod 29 extending substantially through the center ofgravity of the frame 28. Pivots 30, only one of which is visible, areprovided at the ends of the rod 29 and there are suitable bearings, notshown, cooperating with the pivots 30 to permit the frame 28 to befreely balanced about the pivots 30. In order that means fol-vibratingor oscillating the striker frame 28 may be attached thereto an arm orcrank 3| may be secured to the central rod 29 of the striker frame 2|.

For oscillating the striker frame 20 a power driven rocker orosclllatingarm 22 is provided which is connected to the arm 3| by asuitable resilient member such as a spring 33. The relationship betweenthe stiflness of the spring 33 and the moment of inertia of the strikerframe 26 is so chosen that the natural frequency of vibration of thevibratory system formed by the frame 28 and the spring 33 is thefrequency at which it is desired to have the striker bar 22 strike thepointer end 24. That is, the natural frequency of the striker frame 28is equal to the frequency with which dots or marks are to be placed uponthe moving strip chart l5. lected is sufliciently high so that asubstantially continuous record is produced following even sharp andrapid fluctuations in magnitude of the quantity measured by theinstrument l3. The rocker 32 is, of course, oscillated at the samefrequency so that a very small amplitude of vibration of the striker arm22 and furthermore, the striker arm 22 will strike with considerableforce although relatively little energy is supplied by the rocker 32.

In the apparatus described by way of illustration, the rocker 32 isdriven at three strokes per second. In order that the rocker 32 may beoscillated by a revolving motor, a cam arrangement is provided. Therocker 32, which is pivoted at 34, is provided with a fork 35 havingtines extending radially from the pivot 34 to form cam followers. Athree-lift cam is formed by a disk 36 into which three pins 31 areinserted axially l with the pins placed between the tines of the fork35. The disk 36 is mounted upon a shaft 38 of aone-revolution-per-second motor 33. The spacing between the pins 31 ismade such that rotation of the disk 36 carrying the pins 31 producesoscillation of the fork 35 thereby rocking the rocker arm 32. Owing tothe small amount of power required for operating the striker bar 22 inthe arrangement which I have described. the motor may be a relativelysmall motor having a small power consumption such as motors uti lized insynchronous clocks and described in Patent No. 1,495,936-Henry Warren,for example.

For the purpose of causing the strip chart I5 to advance at uniformspeed without need for ad ditio'nal driving power I provide a ratchetchart advancing means powered from the same motor 33 which drives thechart marking mechanism. The chart I5 is rewound on the roll l1 referredto as a re-roll which is pressed by springs l1 against a driving drum 46and, therefore, frictionally engages the driving drum 46, driven fromthe shaft 38 of the motor 33 through a two-stage pawl and ratchetdriving mechanism. The first stage of the'pawl and ratchet drivingmechanism consists of a ratchet wheel 4| cooperating with a movable pawl42 carried at the end of one arm 43 of a U-shaped cradle 44 pivoted inpivots 45 cooperating with bearings, not shown. The remaining'arm 43' ofthe cradle 44 carries at its end a cam follower 46, and thecircumferential surface of the disk 36 on the shaft 33 of the motor 33is cut to form a cam surface 41 cooperating with the cam follower 46.Suitable means such as a spring 48 attached to the pawl 42 are providedfor biasing the cam follower 46 against the cam surface 41 and forresiliently holding the point 43 of the pawl 42 against the teeth of theratchet 4|. The ratchet 4! is carried by shaft 50 journaled in suitablebearings, not shown. At one end the shaft 56 carries crank pins 5| and52 or eccentrics which have axes parallel to the axis of the shaft 56but eccentric thereto. The pin 5| is of relatively large diameter andthe pin 52 is formed as an extension The frequency seof the pin 5| butis eccentric with respect to the pin 5|. The second stage of the pawland ratchet advancing mechanism for the strip chart consists of aratchet 53 secured to the chart driving drum 40 and a pair of pawls 54and 55 cooperating with the ratchet 53 .and pivotally mounted upon thepins 5| and 52 respectively. For resiliently holding the pawls 54 and 55against the teeth of the ratchet 53 suitable means such as springs 56and 51 are provided.

When the apparatus is in operation the rotation of the shaft 38 and thecam surface 41 will produce reciprocating motion of the cam follower 46,as well as the pawl 42, both of which are carried by the oscillatingcradle 44 so that on each rearward stroke of the pawl 42 the ratchet 4|is rotated. Rotation of the shaft 56 secured to the ratchet 4| will, inturn, produce eccentric rotation of the pins 5i and 52 thereby causingthe pawls 54 and 55 to advance alternatively and producing continuousrotation of the ratchet 53. Since one or the other of the pawls 54 and55 is always in mesh with the ratchet 53 backlash, or backward rotationof the driving drum 43 cannot take place.

For the purpose of causing the marking ribbon 2i to advance at a speedproportional to the speed of the strip chart I 5, another pawl andratchet advancing mechanism is provided which is driven from the shaft50. The mechanism for advancing the ribbon 2i consists of a ratchet 58removably connected to the ribbon re-roll spool 26 by a pin 53cooperating with an aperture, not shown, in the spool 26 in a mannerwellknown in the typewriter art." For driving the ratchet 58 there is anoscillating arm 66 having a pawl 6| formed in one end thereof, having asupporting pivot in the form of a screw 62 secured to a portion of thechart carriage, not shown, and having means at the end 63 opposite fromthe pawl 6| for oscillating the arm 66. The oscillating means consistsof a pinion 64 mounted on the rotating shaft 56 and meshing with a gear65 having an eccentric hub whereby the gear 65 is eccentrically mountedupon a pivot 66 formed at the end 63 of the arm 66. For resilientlybiasing the end 63 toward the pinion 64 and holding the pinion 64 andthe gear'65 in mesh, suitable means such as a spring 61 are provided.

As the shaft 50 rotates the pinion 64 will rotateand produce rotation ofthe gear 65 in mesh therewith. However, since the gear 65 is eccentricon its supporting pivot 66 and the spring 61 holds the pinion 64 andgear 65 in mesh, the rotation of the gear 65 will result inreciprocating motion of its pivot 66 thereby oscillating the arm andcausing rotation of the ratchet 58 and the ribbon re-roll spool 26. I

To permit adjusting the speed of travel of the strip chart I5, I mayprovide means for varying the throw of the pawl 42 which cooperates withone of the chart advancing ra-tchets 4|. Such means may consist of rod68 adjustable in its angular position carrying an eccentric disk 63, thecircumference of which serves as a backstop for the arm 43 carrying thechart advancing pawl 42.- To permit adjusting the angular position ofthe rod 68, a resilient arm 10 may be secured thereto having a pin 1|secured at the end thereof adapted to cooperate with any of severalopenings 12, 13, or 14 in one of the side plates l4 of the chartcarriage, only a portion of which is shown in the drawing. By pullingthe pin H out of one of the apertures 12, 13 or 14 and inserting it inanot.-er, the angular position of the eccentric disk 69 may be changedand thus the position of rest of the arm 43 and the pawl 42 may bechanged so as to vary the throw of the chart advancing pawl 42 and thusvary the distance advanced for each revolution of the motor shaft 38.The minimum advance of ratchet I wheel 4| may be one tooth and themaximum advance three or more teeth. It will be observed, however, thatadjustment of the eccentric cam for the purpose of varying chart speeddoes not vary the speed of the rocker arm 32 and for thisreason even theadjustment for very slow chart speed does not interfere with themaintenance of the high speed ofoperation of the striker bar 32 so thatfaithful records of'rapid variations in the measured quantities may bemade with any adjustment of the apparatus. The insertion of the pin llin the apertures l2, l3 and 14 provides for, chart speeds of one, twoand three inches per hour, respectively, the most generally providedchart speeds, as will be understood by those skilled in the art. Thethree-inch per hour speed may be used when the recorder is to beserviced and the record roll is to be replaced weekly, however, one inchper hour is the most common chart speed as this permits monthlyservicing.

With such slow chart speeds in conjunction with continuous record curvesit will be apparent that the length of duration of surges could not beread from the chart for the reason that the width of an ink or pencilline is of the same or greater order of magnitude than the chartdistance corresponding to the duration of a surge. For example, with thecustomary chart speed of one inch per hour, a distance along the timeaxis pf .050 inch, about the closest that can conveniently be measuredon a continuous line chart without special instruments, would correspondto a time period of one hundred eighty seconds or three minutes. In myapparatus producing three dots per second, however, measurements insurge records of time periods as short as one second can readily be madebecause when the measured quantity rises or falls very rapidly therecord curve is drawn out sidewise so as to separate the dots laterally.By'counting the dots, the duration of the entire surge and the durationof portions of the surge may readily be ascertained because each dotrepresents a fixed time interval, in this case one third secondirrespective of the chart speed. Thus there are coarse and finemeasurements of time duration, small scale for values read under steadystate conditions and large scale for surge conditions. With the ordinarychart speed of one inch per hour and providing three strokes per secondof the striker 22, my apparatus provides one stroke of the striker orone dot for each ten thousandth inch of chart travel or more exactly,10,800 dots per inch of travel. Thus the dots actually overlap in thelongitudinal direction when the measured quantity remains constant orvaries gradually. But in the case of surges, the pointer moves sorapidly that the dots are spread out laterally and may readily bedistinguished and counted. I consider the most useful. speed of dottingto fall between one and ten dots per second so that with chart speedsfrom one to three inches per hour the most useful ratios of chart speedsin inches to dotting speeds in dots per second fall between 1: 1200 and1236,000, preferably between 1:3600 and 1:36,000.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention together with theapparatus which I now consider to represent the best embodiment thereofbut I desire to have it understood that the apparatus shown is onlyillustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a chart recorder of the intermittent marking type having a markingstrip and freely movable arm, a movable striker for producing contactbetween portions of the marking strip and a chart adjacent said movablearm, a power driven reciprocating rocker for oscillating said strikerand a resilient connection between said rocker and said striker, thefrequency of operation of said rocker and the stiffness of saidresilient means and moment of inertia of said striker being so selectedthat natural frequency of vibration of said striker substantially equalsthe frequency of reciprocation of said rocker.

2. In a recorder having a casing with an exposed substantially fiatfront face and a strip chart movable vertically along said exposed frontface of the casing, the combination of, a platen in front of said stripchart, extending across the chart along its surface, a marker stripbetween said platen and said chart extending along the platen, an armbehind said chart movable in response to variations in indications to berecorded, said arm being transversely movable in a plane parallel to thesurface of said chart and along said platen, and a striker behind saidarm for driving said arm and a portion of said chart against said markerstrip and said platen, whereby no mechanism which deflects is requiredin front of the chart plane, said arm is in a protected location and thechart may be examined or pulled back without interference.

3. In a recorder having a casing with an exposed substantially flat faceand a strip chart, movable along said exposed face of the casing in aplane, which plane forms one of the boundaries of the volume enclosed bythe casing, the combination of a platen in front of said chart,extending across the chart along its surface, a marking element betweenthe platen and the chart incooperative relation with the platen, an armbehind said chart movable in response to variations in indications to berecorded, said arm being transversely movable in a plane parallel -tothe surface of said chart and to said platen,

and a striker behind said arm for driving said arm and a portion of saidchart against said marking element, whereby no mechanism which deflectsis required outside the boundary of the casing volume formed by thechart plane, said arm is in a protected location and the chart may beexamined or pulled back without interference.

RALPH G. AREY.

